Human milk is generally recognized as an ideal feeding for most infants due to its overall nutritional composition. It is well known and generally accepted that human milk provides infants with unique immunologic and developmental benefits as compared generally to commercially available infant formulas.
For some infants, however, especially preterm infants, human milk does not always meet the complete nutritional needs. Although these infants still generally benefit from human milk, it is often desirable to supplement their human milk feedings with additional nutrients. Initially, these preterm infants may grow more rapidly than many of their term counterparts, and accelerated growth often requires additional nutrition, which is made possible by the use of a human milk fortifier in combination with human milk.
Most of the human milk fortifiers described in the literature and commercially available have been formulated as reconstitutable powders rather than liquids in order to minimize the volume displacement of human milk by the fortifier. Recently, however, liquid human milk fortifiers, and specifically highly concentrated human milk fortifier liquids, have received more attention as an alternative to powders. Although these highly concentrated human milk fortifiers do generally displace slightly more volume that the conventional powders, the liquids have the significant benefit of being commercially sterile as they can be subjected to sufficient heat treatment during manufacturing, including aseptic manufacturing.
It may be advantageous to utilize hydrolyzed proteins in human milk fortifiers. However, as compared to intact proteins, extensively hydrolyzed proteins (i.e., proteins having a degree of hydrolysis of about 20% or more) tend to have poor ability to form long term stable emulsions. Additionally, the presence of high levels of insoluble minerals such as calcium salts may also cause a number of stability issues when used in combination with extensively hydrolyzed proteins. As such, manufacturing long term stable liquid concentrated human milk fortifiers including extensively hydrolyzed proteins have proven difficult.
Many liquid human milk fortifiers have been manufactured with stabilizers, such as carrageenan. The stabilizers act to hold the nutrients and insolubles in solution over time and thus improve long term stability of the product. Although stabilizers such as carrageenan have generally proven to retard precipitation of many ingredients in the liquid nutritional formulations, these types of stabilizers are not permitted in infant formulas and human milk fortifiers in many countries around the world. When stabilizers cannot be used in highly concentrated human milk fortifiers, it can be very difficult to produce a long term stable highly concentrated human milk fortifier.
As such, there is a need for highly concentrated liquid human milk fortifiers that are sufficiently long term stable that include hypoallergenic proteins, such as extensively hydrolyzed casein proteins. Additionally, it would be very beneficial if the highly concentrated human milk fortifier could be formulated to provide additional macro- and micro-nutrients without unwanted mineral fallout during storage.